(1) Field of the Invention
The present invention relates generally to a method of communicating data by micro-modulation of the DC power supply voltage. Digital data is encoded in micro-modulation of the DC voltage between an electrical device and a microcontroller with which communication is to be established.
(2) Description of Related Art
There are a number of conventional methods and devices in commercial practice for transmitting signals over alternating current (“AC”) power lines, particularly within households or commercial buildings, for use in controlling lights, appliances, and other devices, generally within the same building. Many of these methods involve modulating higher frequency signals (e.g. radio frequency (RF) signals) onto AC power lines that then travel the power lines where the higher frequency signals are received by a receiver and control device. Such techniques involve several additional circuits and devices and costs associated therewith. In some cases, the control and distance capabilities, and costs, are greater than what is required for many applications, such as controlling the intensity of lighting.
Current methods of modulating a DC power source between two voltages, such as 4 volts and 5 volts, are established in the prior art. One method of modulating a DC power source between two voltage levels is the use of a shunt regulator, which draws sufficient current from the source to cause the voltage to be reduced to the value of the referenced voltage. A shunt regulator is a one-way communication device, so multiple shunt regulators may be necessary for a particular application. If the reference voltage input to the shunt regulator is varied between 4 and 5 volts, then the voltage supplied to the microcontroller will be varied in the same manner. Likewise, any microcontroller being powered using a shunt regulator may also send data through the use of similar shunt regulator. When utilizing multiple shunt regulators, standard half-duplex protocols may be used to prevent collisions between multiple devices so that only one device is permitted to control the data transmitted at any one time. The use of shunt regulators increases the cost of production of an electrical device. And, the volume of each shunt regulator incorporated into a device may necessitate the increase in overall volume of the device and packaging for the electrical device.
The invention disclosed herein allows the transfer of digital data through the utilization of two non-zero DC voltage levels. The invention herein allows for the transmission of digital data while eliminating the need for one or more shunt regulators. The method herein utilizes the DC voltage that encodes the digital data to also function to power the microcontroller. The invention herein allows a significant reduction in the number of external components, such as required for implementation of competing prior art techniques. The reduction of external components, provides added value to the electrical device because of a reduction in the cost associated with manufacture of the electrical device, a reduction in the volume that must be packaged, and an increase in the reliability in performance of the electrical device. The external components required for the implementation of competing techniques may require a much larger volume than the microcontroller utilized in this method. And the cost of the microcontroller herein is significantly less than the costs of the external components required to communicate digital data in competing techniques known in the prior art.
Godbole (US 2009/0160627 A1) discloses the modulation of an alternating current and rectified alternating current, also known as pulsating direct current, by modifying phase angles to transmit data corresponding to control commands via a power line transmitting AC. In the Godbole method, control data is mapped to specific firing phase angles. For example, Godbole suggests mapping data to the set of 5°, 10°, 15°, and 20°. In one Godbole embodiment, a table in memory includes an association of firing phase angles to data bits, or of firing phase angles to specific commands. Godbole provides for the encoding of data in the firing phase angles of the rectified AC (pulsating DC) via voltage or current changes. AC and rectified AC are limited to just one phase modification per cycle, which occurs 60 times per second. Thus, the method of Godbole only permits encoding of data at a rate of 60 times per second. The method herein encodes data on small changes in non-zero voltage which is constant and not subject to phase modifications. The technique herein may be successfully applied at much higher frequencies that may exceed 75 KHz, or more than 1000 times faster than AC line frequency. The invention herein permits the encoding of potentially thousands of bits of data per second. Additionally, power surges or interruptions could lead in improper coding of data.
Lapidus (U.S. Pat. No. 7,058,823 B2) discloses system-on-a-chip and other large scale integrated circuit devices that are capable of operating at high frequencies while minimizing power consumption. Lapidus provides for devices that are capable of switching to a low power mode when high performance is not required. Lapidus provides for varying power supply voltage levels to reduce power consumption when high performance is not needed. Lapidus discloses a line driver for receiving an incoming data signal and transmitting an outgoing data signal on the signal line; (2) a power source for supplying a plurality of power voltage levels to a power supply rail of the line driver; and (3) a power level controller for determining a data rate of the outgoing data signal and in response to the determination, selectively applying one of the plurality of power voltage levels to the power supply rail fo the line driver to modify the amplitude fo the outgoing data signal. This patent is designed for use in an integrated circuit, using separate signal and power lines. Data is transmitted in Lapidus by the presence or absence of a signal level that can be changed as circumstances require. Lapidus differs significantly from the invention herein. In the device of Lapidus there is no correlation between the level of the signal and the transmitted data. In the present invention, the non-zero DC voltage level encodes the digital data.
Cusey (U.S. Pat. No. 6,239,732 B1) discloses an integrated circuit having analog to digital conversion circuitry capable of receiving a plurality of analog signals and converting them to a digital value. The digital value is then transmitted, upon request, over a single wire bus. The method of Cusy differs significantly from the invention herein. Cusey sends electrical power over a data line. While in this invention, data is sent over a power line.